Abstract: Speciation of nanoparticles, that is, their differentiation based on size, shape and stabilizing shell is becoming important since their properties depend on these parameters. Nanoparticle-imprinted polymers (NIPs) are a new approach that aims to selectively recognize nanoparticles based on their structural properties. In this study, monolayers of cellulose acetate (CA) accommodating gold nanoparticles stabilized with dodecanethiol (AuNPs/C12) are transferred onto indium tin oxide (ITO) by the LangmuirGă˘Blodgett technique. One to five monolayers are assembled. Electrochemical oxidation dissolves the AuNPs/C12 to form cavities in the films, which fit the size and shape of the AuNPs/C12. Reuptake of the nanoparticles from a solution is successful using the imprinted films, whereas the control films containing only CA layers do not reuptake the AuNPs/C12. The NIPs are highly selective and other gold nanoparticles stabilized by other thiols are not recognized by the imprinted matrixTemplate and target information:nanoparticles, gold nanoparticlesAuthor keywords:gold nanoparticles, imprinting, Langmuir films, polymers, shell-selective matrices